html,
body,
#app,
.container {
    height: 100%;
}

.container {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.container .box {
    flex: 1;
    overflow: auto;
    background-color: #fff;
}

.container .footer {
    height: 44px;
    background-color: lightblue;
}